From deception trials to control reagents. The introduction of the control group about a century ago

This is the story of the remarkable psychologist John E. Coover, who, in the early 1900s, was the first to advocate the comparison of experimental and control groups as a methodological necessity. Moreover, the author raises the issue of why control groups were launched about a century ago, and why psychology was comparatively early in codifying group comparison as a methodological routine. In dealing with these questions, the author discusses the relations between turn-of-the-century science and society as well as between psychophysical research and educational experimentation. Furthermore, the mystery is solved of how Coover's rightful place in the received history of experimental controls could be taken by precisely the authors whom he criticized for the lack of controls.